proc: introduce proc_create_seq_private

Variant of proc_create_data that directly take a struct seq_operations
argument + a private state size and drastically reduces the boilerplate
code in the callers.

All trivial callers converted over.

Signed-off-by: Christoph Hellwig <hch@lst.de>
diff --git a/include/linux/atalk.h b/include/linux/atalk.h
index 4037392..23f8055 100644
--- a/include/linux/atalk.h
+++ b/include/linux/atalk.h
@@ -145,7 +145,12 @@ extern rwlock_t atalk_interfaces_lock;
 
 extern struct atalk_route atrtr_default;
 
-extern const struct file_operations atalk_seq_arp_fops;
+struct aarp_iter_state {
+	int bucket;
+	struct aarp_entry **table;
+};
+
+extern const struct seq_operations aarp_seq_ops;
 
 extern int sysctl_aarp_expiry_time;
 extern int sysctl_aarp_tick_time;